Video: Culture Secretary Jeremy Hunt teeters above 400-ft Yorkshire mine shaft

The 460ft-deep shaft – believed to be the only one of its kind still in existence – was on the brink of collapse five years ago.

Now, after an £870,000 restoration project, visitors can peer down the chasm through a new toughened glass cover while those deep underground can gaze up at the pinpoint of light from the surface above.

Mr Hunt appeared surprised as the shaft was lit up to reveal the scale of the gaping abyss beneath him yesterday.

“I’ve realised the drop is a bit bigger than I thought,” said the Minister, who has fought to hang on to his job after a row erupted over his dealings with the Murdoch empire.

“Don’t look down! It’s absolutely amazing,” Mr Hunt said yesterday.

His department paid £150,000 towards the conservation, which he said would be “transformative” for generations of school children who will visit the museum, on the site of the former Caphouse Colliery in Overton, near Wakefield.

“It’s going to tell them about their heritage, about the sacrifices of the people who became miners for very many years, the hard work and the risks,” he said.

“And I think it will make them think about their futures, and about the importance of strong communities, which was what being a collier was all about.”

The cash from the Department for Culture, Media and Sport was matched by the Department of Trade and Industry and used as partnership funding for a successful bid to the Heritage Lottery Fund.

“The National Coal Mining Museum is hugely important in preserving a key part of our nation’s industrial heritage,” said Mr Hunt.

“The opening of the new furnace shaft will make it an even more fascinating and informative experience for visitors.”

The furnace shaft would originally have ventilated the former pit, with a fire lit at the bottom sending warm air up and drawing in fresh air down the main riding shaft, more than 100ft away.

Engineers were challenged with finding ways to ensure safe access for visitors at the base of the shaft while covering the top without obscuring visibility.

The work took around eight months following approval by the Heritage Lottery and the Mines Inspectorate.

Baroness Estelle Morris, chairwoman of the National Coal Mining Museum and former Minister for the Arts in the Department for Culture, Media and Sport, said the opening of the “unique and exciting” new attraction marked a great moment in the museum’s history and enhance visitors’ experience.

“The previous shaft was in desperate need of repair, and had we not repaired it there was a risk that our other shaft wouldn’t have been able to take visitors down,” she said. But I think more than that, I actually think it’s a thing of beauty, which seems a strange thing to say about brickwork, but the craftsmanship that’s brought that about matched with the craftsmanship there was generations ago in mining makes a really, really good visit for local people and I think they’ll enjoy it.”

Newly-refurbished displays were also unveiled yesterday in the museum’s lamproom.

The former colliery workshop is now where visitors are given their hard hats and lamps as they first venture underground for tours led by ex-miners.

Baroness Morris said: “The newly refurbished shaft and lamproom displays are fantastic additions to the museum’s existing range of collections.”